The primary goal of the research program is to extend our understanding of the role of psychosocial factors in susceptibility to upper respiratory infectious illness. The award allows the investigator (a social psychologist by training) to extend his background in biological, statistical, and methodological areas directly relevant to his research goals. Dr. Cohen has spent his career studying the influence of psychological stress and social supports on mental and physical health. He has made a range of theoretical and empirical contributions and trained over a dozen contributing scientists. With the help of the K02 award, he has received training in basic biological processes and established a research program examining the role of psychosocial factors in infectious disease. He is asking for continued support to expand his expertise in a range of areas relevant to his research plan. The primary aim of this proposed study is to evaluate the roles of social networks, relationships, supports, and interactions in susceptibility to upper respiratory infections. It also attempts to identify causal pathways (psychological, health practice, and endocrine linking these factors to disease susceptibility. Before being intentionally exposed to an upper respiratory virus, 320 volunteers are administered measures of the psychosocial predictors. These factors are assessed with interviews, questionnaires, and daily-diaries. Health-practices, affects, cognitions, and endocrine response are also assessed as potential pathways linking networks and supports to host susceptibility. After these assessment procedures are completed, subjects are exposed by nasal drops to one or two rhinoviruses, quarantined and monitored for infection and symptoms for five days. Analyses focus on whether psychosocial factors predict who develops clinical illness (verified infection plus clinical diagnosis) and whether these relations are explicable in terms of affective, cognitive, endocrine, and health practice mediation. Outcomes based on two definitions of clinical diagnosis, objectively assessed signs of disease, and patient reports of symptoms and disease, are studied and contrasted.